I'm winding a secondary, nominally 12.75x60". A 10lb spool of 22awg only got me 42". I'm thinking about splicing another spool onto the end to get to 60". Could this be reasonably done, or should I just take the performance loss of a too short secondary?

So, I'm at college now and found there are Lots of free bits at the makerspaces around here, so with spare parts from a medium sized coil I built over the summer, I built this little guy.

Coils: 5.5 ish turns of 12awg for primary, exact tuning doesn't seem to matter much. I have no clue what the secondary is, but it's likely an early onetesla secondary. 2.375" OD, 6.25" height, arbitrary sized 3d printed toroid on top (I think 1.6x6.2?); basically zero effort put into the coils. The secondary has a bunch of holes in the insulation and a tendency to flash over and I could use a taller one, so it's prone to replacement once it burns out (2 candidates in the Bin Of Old OneTesla Secondaries I found this one in). Supports laser cut from 6mm acrylic.
Fres: 230khz, coupling: no clue but probably at least .2; barely low enough to not arc over.


Inverter specs:
BSM150 half bridge
300A OCD
I designed it for doubled (120v) mains input, but with the on times I'm using, increasing past normal rectified mains gives no performance boost and only increases flashovers, so normal rectified mains (~150Vbus) is perfectly adequate
100nF dawncap
UD2.9 w/ pulseskip
2x 200V 2200uF bus caps in series






I'm using mostly TMax midistick for the interrupter with 12% duty cycle max, 1000uS on time max. It gets warm but I can run it for 5 to 10 minutes continuous before it starts getting uncomfortably warm. The inverter is passively cooled and heats up ever so slightly faster than the coils themselves, so I get plenty of runtime especially if it's cool out and the inverter's 80C thermal switch trips before any damage can be done. I'm not sure how much power it uses as I don't have a working ampmeter, but I haven't tripped any breakers and the 18awg input cables get warm so I'd guess between 5 and 10 amps.

Videos:
https://youtube.com/shorts/gyPdY8dJFyg
https://youtube.com/shorts/9rdtgXvGxZM

Max recorded arc length is 17", and anything around 12" or below is thick and bright; the breakout point is quite discolored from the heat.
I built this coil to be portable, easy to run, and reliable for showing friends and family what tesla coils are like. Aside from the secondary on its last legs, I'm very happy with it so far.

I may try 2000us soon and see just how high can I go with this little guy, but for now another project (hint: Big drsstc) has priority.

I'm working on a very large drsstc. As the days of 150A GTO snubbers are unfortunately over, it's either $500 worth of dawncaps, $1000 worth of cde942's, or something one of yall can sell me. I'm looking for enough capacitor to have ~1uF +- .5uF, >15kV, >300Arms. >200Arms may be acceptable if it's easy enough to aggressively cool.

Thanks

I'm building a drsstc with a ud3 driver, which can monitor 10k NTCs for thermal protection. My half bridges each have integrated 5k NTCs. Can I put them in series and expect them to act like a single 10k? If not, what would I need to do to make the ud3 work with one of the 5k's?

I'm designing a big coil, and a point was brought up - during operation, full bus voltage is across a pair of gdt windings at all times. I'm hoping to use a boost converter for a bus around 1200v and cat5 wires have 300v insulation, so I don't want to risk a gdt flashover destroying my igbt gates. Are there any other cable standards like cat5 but rated for a sufficiently high voltage, or will I have to use individual wires?

I've been having some problems with my primary coil heating up very quickly. It uses EVR's supports, and I'm running it at 400A OCD and 300us/12% duty cycle max. After a few minutes, the primary is hot enough to soften the polycarbonate and melt the plastic end caps. The aluminum frame also gets fairly warm, though there are no large loops. Is this reasonable/inevitable with those on times or does it sound like something else is going on?
Thanks!

Ok, so I got my drsstc working, and now have no clue how to tune it properly.
Specs:
BSM150 full bridge (with excessive cooling)
340V bus
.3uF mmc (2s6p cde940)
rather fat secondary, 3.33:1
ud2.9+ with pulse skip
almost exactly 50k secondary reactance at resonance (180kHz)
coupling of .131
attached is a picture of the coil

My questions is how do I optimize it for arc length and sound quality?
I've seen a few coils with conservative ocd and very long on times/duty cycles getting huge arcs with pulse skip, but my current impression is that that's only feasible for low notes, making it unsuitable for music.
So, how should I tune it? low current and high on times or vice versa, or is high current and on time feasible?
And how should I determine the ocd? By guessing based on thermal dissipation?
This seems like fairly basic information, but the tuning section of kaiser's guide is unfinished and I'm having trouble finding other resources.
Any help or links to resources would be appreciated.

edit: this is the best I've gotten so far: https://drive.google.com/file/d/1KTiZVL3Kdm18simvhhEKExdP0c7ETTkH/view?usp=sharing
This is using TMax's midi stick with ocd at 300A, Vbus~100v, max on time 150us, max duty cycle 8%
The ocd is the yellow light above the red one, and it's continually tripped here.
The ocd similarly remains almost continually tripped for lower notes, but they sound strange, quiet, hardly any arcs, and they produce weird harmonics.
I'm not sure what it is about the high notes that makes them and only them sound normal.

I'm trying to tune zvs on my tesla coil (bsm150 full bridge, 300A ocd, ud2.9), and the way I read to do this was to minimize ringing on the bridge output. Scoping the output got me the attached image, which seems off to me. Shouldn't it more or less resemble a square wave? The signals to the gates were all normal. Any ideas?

It looks like maybe the transistors are turning on too slowly? Which doesn't really make sense because the design is based on franzoli electronics' alphaDRs, and I used the same igbts and 5.1ohm gate resistors he did.

I have a 24v power supply and a line filter, both of which have grounded housings. Should I connect these to my house ground, the coil ground, or leave them floating? Connecting them to the coil ground doesnt seem optimal, as it couples that to the house lines and neutral through the line filter(s)

I roughly followed loneocean's drsstc 3, and am having the same problem he described having with the gates of each igbt briefly switching polarity and then ringing while turning on. He described the solution to the problem being to lower the gate resistance. My gate resistors are currently 5.1ohm. Should I lower them, and to what value?